[stm32f4-discovery] Added timer example for the stm32f4 discovery board. #79
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Yeah, that is why I wrote the timer_get_frequency function: libopencm3/libopencm3#286. But this is basically the same for F1! |
| tim_setup(); | ||
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| while (1) | ||
| __asm("nop"); |
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__WIF(); would be cool instead maybe?
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You mean __WFI();? I did not know about this assembly call. Good to know. Thanks for pointing it out. I will use that. For those reading this. To save you time searching what this is. It stands for "Wait For Interrupt" and is a hint instruction that suspends execution until one of the following events occurs:
- a non-masked interrupt occurs and is taken
- an interrupt masked by PRIMASK becomes pending
- a Debug Entry request
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0552a/BABFEFIG.html
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@flixr OK that is really embarrassing that I did not know that it was the same case for the stm32f1 too. You have just blown my mind here. 😊 I think the right way of dealing with that would be to update the way rcc is being set on the f1 to be in the style of f4 and pull that information from the setup struct. I will explain what I mean in a separate pull request, with the proposed changes. For now I think this patch should be ok until we have something in the style of what you proposed or a variation on that in place... |
WFI (Wait for Interrupt) tells the processor to suspend untill the next interrupt is called. Better than burning away the cycles with nop.
This example exposes an interesting difference between f1 and f4. The clocks for the timers are not exactly the same ones as for other peripherals.
Oh JOY! :)